Abstract
Gene amplification mutations, where a genomic segment is abnormally copied many times, occur spontaneously in all life forms and are important drivers in cancer, pathogens, and evolution. Despite this, the detailed mechanisms of their formation remain largely unknown in all organisms. I predict that factors involved in endogenous DNA break-repair processes contribute to gene amplification development. To investigate this, a bacterial model system is used in Acinetobacter baylyi, where spontaneous mutants carrying de novo high-copy gene amplification encompassing cat genes are exclusively selected on minimum benzoate agar plates. Using this system, this project examines three possible internal influences of DNA breaks and repair on the ability to form gene amplification mutations: 1) transposable elements, 2) R-loops, and the 3) RecBCD enzyme. Specifically, various growth mediums and gene knockout strains were utilized to observe impacts to gene amplification frequencies. Preliminary results indicate removal of transposable elements decreased cat gene amplification mutant frequencies by over 25-fold, stimulating R-loops increased amplification over 18-fold, and rendering a major DNA-repair pathway, recBCD, nonfunctional completely stifles gene amplification. Together, these three experimental findings provide consistent evidence that DNA breaks and their repair mechanisms are key factors involved in forming gene amplification mutations. Future research will focus on continuing to develop a more detailed model for gene amplification progression, which could eventually inform preventative methods and treatments for numerous diseases.